A sealing device with a tone wheel formed to seal between a fixed side member and a rotating side member. A slinger comprises a fitting cylindrical part fitted to the rotating side member and a flanged part radially extendedly formed at one end part of the fitting cylindrical part positioned on the outer side of a sealed portion. The outer surface of the flanged part positioned on the outer side of the sealed portion comprises a tone wheel stuck surface on which the tone wheel formed of a magnetic ring is stuck integrally with each other and an extended surface on which the tone wheel is not stuck and extended to the fixed side member. The sealing device is characterized in that a core comprises at least a fitting cylindrical part fitted to the fixed side member, the one end part of the fitting cylindrical part positioned on the outer side of the sealed portion is projected from the outer surface of the flanged part of the slinger to the outside, a part of the seal lip part is formed to be brought into elastically slidable contact with the extended surface of the slinger from the outside, and the flanged part is held by the seal lip part and the other seal lip part from the inside and the outside.